In a tomograph of the type used in reconstructive tomography, a beam of radiation passes through an object; and a detector receives that beam. Relative movement is provided between the beam of radiation and the object to provide a proper tomographic examination of that object.
Zacher application Ser. No. 636,104 for X-Ray Detector which was filed on Nov. 28, 1975, the disclosure of which is incorporated by reference herein, shows and describes an X-ray tomograph wherein an X-ray source is mounted on a rotatable support at one side of an object-receiving area and wherein a detector is mounted on that rotatable support at the opposite side of that object-receiving area. Rotation of that rotatable support relative to that object-receiving area enables pulsed X-ray beams from that X-ray source to be rotated relative to an object within the object-receiving area while those X-ray beams are passing through that object. That rotatable support is continuously rotatable in one direction; and the object can be repositioned axially at the end of each complete rotation of that rotatable support. As a result, an examination sequence of several rotations of that rotatable support can be conducted on a continuous basis. The X-ray tomograph of the Zacher application is valuable and useful. However, rotating reconstructive tomographs of the type having the relationship between the detector and the radiation source fixed have inherent artifact problems. See G. N. Hounsfield, "Picture Quality of Computed Tomography," American Journal of Roentgenology, Vol. 129, pp 3-9 (1976).
The present invention improves the X-ray tomograph of the said Zacher application by mounting the X-ray tube so it can move in a predetermined path relative to the object-receiving space by giving the predetermined path of the X-ray tube a center, by mounting the detector so it can move in a second path relative to that object-receiving space, bygiving the detector a center which moves in the path of the X-ray tube, and by interrelating the movement of that X-ray tube and of that detector so the source of the X-ray beam and a point on that detector define a succession of translated, parallel lines, which pass through the object-receiving space, as that X-ray tube and that detector move, respectively, through the predetermined and second paths. Such construction eliminates artifacts of the type disclosed by Hounsfield and greatly reduces problems caused by inconsistent detector calibration.
Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.
In the drawing and accompanying description, preferred embodiments of the present invention are shown and described but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claims.